How ground screws work
A steel screw is driven into the ground down to the design depth and becomes the bearing base for the structure. No digging, no concrete, no waiting: T-Block® takes the structure straight away and at the end of its life it is unscrewed.
What they are, where they are used and how they compare with concrete: the complete guide to ground screws.
The principle
A screw foundation is a steel shaft with helical flights welded to its lower part. The flights act as bearing surfaces spread out at depth, and the shaft adds friction with the surrounding soil: together they hold the structure in every direction.
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Screwing in
The screw goes into the ground by turning. The helix passes through the soil without removing it: the soil stays where it is and the screw reaches the required depth.
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Bearing
At the design depth the screw takes the load. How much it carries depends on three things: the type of soil, the geometry of the helix and the depth reached.
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Fixing
The structure is fixed on the head of the screw with a flange, bracket or fork. There is no concrete to cure: you build as soon as the screw is at level.
The stages of a job
The sequence is the same for a garden fence and for a solar farm. What changes are the tools, depending on the number of points and the screw model.
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Stage 1: Setting out and pegging
The points where the screws will go are marked on the ground at the spacing set by the design.
Small jobs, manual installation
Tape measure, string line, pegs and a spirit level. Enough for a few dozen points.
Large numbers
Rotating laser level for the heights; total station or GPS for complex layouts.
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Stage 2: Pilot hole
in most soilsA small-diameter hole, not an excavation: it clears surface stones, reduces the effort and helps the screw start vertically.
Normal or compact soil
Rotary hammer drill with a pilot bit.
Hard ground, rubble, rock
Breaker or rotary-percussive drill down to working depth.
Loose or sandy soil
Usually not needed: the screw starts on its own.
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Stage 3: Screwing in
The screw is turned clockwise down to the design depth. The method depends on the model and on the number of points.
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By hand
Socket with T-handle or a dedicated wrench. Up to the T6 series models.
1–2 people · no machine
How it is done -
Electric driver
High-torque driver with socket and reaction bar. Quiet, no excavator. Up to the T7 series.
1 person · light equipment
How it is done -
Excavator with rotary drive
Hydraulic rotary drive on the arm of a mini excavator, for large jobs and for the series above T7.
1 person + machine
How it is done -
Tracked mast machine
The mast holds the T-Block vertical; pilot hole and screwing in on the same machine. For fields with many points in a row.
1 person + machine
How it is done
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Stage 4: Checks
Once the screw is in, the points that matter for fixing the structure are checked.
- Height: the head is at the planned level
- Plumb: spirit level or digital inclinometer
- Torque: read and recorded at the end of screwing in, when the design requires it
Stage 5: And when the structure is no longer needed
The screw is turned anticlockwise, with the same equipment used to install it. No block is left in the ground to break out and nothing goes to landfill: unscrewed, the screw leaves no trace and the area is free again.
Installation methods
Four ways to screw in a T-Block, from a garden to a solar farm. The choice depends on the number of points and on the model.
Load testing
The values on the data sheets are design estimates. When the project needs a figure measured in that soil, a few T-Block ground screws are tested directly on site, under real load.
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The compression test
A jack pushes the T-Block down, against a beam fixed on two anchor T-Blocks; dial gauges measure how far it settles.
How the test is done -
The pull-out test
A jack on a tripod pulls the T-Block upwards, as the wind does; the force and how far it rises are measured.
How the test is done
See it done, in under two minutes
A hand installation from start to finish: the screw, the wrench, the ground. It is easier to understand by watching it.
Member area
Data sheets, catalogue and load calculator
For designers, installers and customers: free registration, subject to approval. The member area is in Italian.
Which T-Block to choose
By application
Decks, fences, solar, signage and all the other applications: start from what you need to support.
By load
Four load ranges, from the light one for single fixings up to the T10 and T15 series for the highest loads.
By soil
Sandy, silty, compact, peaty, with rubble: for each soil, the models that perform best.
Not sure about your soil?
Tell us what you need to install and where: we will help you choose the model and the installation method.
Contact us